Fig. 54.—Transverse section of a part of the leaf of Aristida setacea. × 30.
1. Vascular bundle; 2. sclerenchyma; 3. motor cells.
Fig. 55.—Transverse section of a portion of the leaf of Aristida setacea. × 120
1. Motor cells; 2. stomata; 3. sclerenchyma; 4. epidermis; 5. cutin layer.
The sclerenchyma lying on the lower side of the primary bundles are contiguous with the bundle, while those above are separated from the bundle by the chlorophyllous layer. (See fig. 55.) In the case of secondary and tertiary bundles the sclerenchymatous bands lying on the lower side are in contact with the chlorophyllous layer, whereas the upper bands are either in contact with this layer or separated from it by a few parenchymatous cells.
All the vascular bundles in the leaves of Eragrostis Willdenoviana are provided with sclerenchyma on both the sides. The lower band of the primary vascular bundles is continuous with the vascular bundle, the chlorophyllous layer being open below. The upper bands of the primary and the lower bands of the secondary vascular bundles just touch the chlorophyllous layer. In the secondary bundles the sclerenchyma band above is separated from the chlorophyllous layer by two layers of parenchyma. In the case of the leaves of Panicum flavidum, P. colonum, P. fluitans and Pennisetum cenchroides the sclerenchyma is separated from the chlorophyllous layer by layers of parenchyma.
Fig. 56.—Transverse section of a part of the leaf of Eragrostis Willdenoviana. × 30
1. Vascular bundle; 2. sclerenchyma; 3. motor cells.